EVALUATION OF GENERAL ANESTHETICS IN RELATION TO TRIGEMINO-AUTONOMIC REFLEX

通过电刺激三叉神经，研究了全身麻醉剂对三叉神经抑制反应（TDR）的影响。这些研究是在成年日本大白兔上进行的，用聚氨酯和α -氯代蔗糖麻醉。气管插管并将导管置入股动脉。由股动脉压力波计算动脉压和心率。用10S方波脉冲（持续时间0.5mS）刺激心神经。记录颈交感神经和迷走神经的神经活动。在初步研究中，我们确定了诱发三叉神经抑制反应的最佳频率和强度范围为5Hz和5-20mA。在这项研究中，心理神经受到这些方式的刺激。我们检查了两种挥发性麻醉剂（异氟醚和七氟醚）和一种静脉麻醉剂（异丙酚）。在异氟醚和七氟醚中，随着麻醉浓度的升高，血压下降的程度越小。TDR在0.75 ~ 1.0 MAC（尾夹法）几乎消失。在Guedel临床征象中，尾翼静止法的1.0 MAC相当于第三期的第3或第4位。提示抑制TDR所需的异氟烷和七氟烷浓度相当高。另一方面，异丙酚对TDR的影响最小。在高剂量125 mg/kg/hr的情况下，神经刺激引起的血压下降率约为8%。因此我们得出结论，异丙酚不能完全消除TDR。建议在口腔外科手术中应用异丙酚全麻时，适当阻断有害刺激是必要的。

We investigated effects of general anesthetics on trigeminal depressor responses ( TDR), which were evoked with electrical stimulation to trigeminal nerve.These studies were performed on adult Japanese White rabbits, anesthetized with urethane and alfa-chioralose. The trachea was cannulated and a catheter placed in femoral artery. Arterial pressure and heart rate were calculated from pressure wave of femoral artery. Mental nerve was stimulated with 10S train of squarewave pulses (0.5mS duration). Records of nerve activities were obtained from cervical sympathetic nerve and vagal nerve.In preliminary study, we determined that the optimal frequency and intensity range which evoked trigeminal depressor response was 5Hz and 5-20mA.In this study, mental nerve was stimulated in these manners.We examined two volatile anesthetics (isoflurane and sevoflurane ) and one intravenous anesthetic (propofol).In isoflurane and sevoflurane, degree of fall in blood pressure became smaller as inspired concentration of anesthetics became higher. TDR disappeared in almost 0.75-1.0 MAC ( tail clamp method). 1.0 MAC of tail calmp method is said to be equivalent to plane 3 or 4 of third stage in Guedel's clinical signs. It is suggested that concentration necessary to suppress TDR is rather high in isoflurane and sevoflurane.On the other hand, effects of propofol on TDR were minimum. In administration rate of 125 mg/kg/hr, which was extremely high dosage, about 8% of fall in blood pressure evoked with mental nerve stimulation was observed. So we concluded that propofol could not disappear TDR completely. It is suggested that proper blocked of noxious stimulation is necessary when general anesthesia is performed with propofol for oral surgery.